Well, do you really think that we 'd be as developed as we are now, if there were no oil?
Think of the things, that use oil. All these wont be able to work again. Maybe they might, because we keep on developing with time, for eg: cars... we are developing means to make it run on electricity and bio-fuel. but then, the airplanes cannot run on these things, they need oil. Sure we might adapt to a situation without oil... but it 'll take us a while to do us. and by "a while", i mean.. a lot of time! ;)